Electric switch



Aug. 14, 1928. 1,680,568

J. POLLAK ELECTRIC SWITCH PATENT OFFICE.

JOSEPH IOLLAK, 0F BOSTON, MASSACHUSETTS.

ELECTRIC SWITCH.

Application filed January 2, 1926. Serial No. 78,840.

The present invention is concerned with an electric switch designed for detachable attachment to a support of suitable character, and comprising the necessary electrical contacts enclosed in a casing of simple construction, involving a minimum number of parts, but having the eifect of completely and securely enclosing and protecting such contacts. Among other uses to which the invention is intended to be applied, is application to the instrument board of an automobile, either in a visible or concealed position, and with capacity for instant attachment and detachment. The invention consists in a switch having the features above referred to and containin other structural features, which will be escribed in the following specification.

The original drawings filed with this specification show the preferred form or embodiment of my switch and its casing, on a scale larger than the actual size of such preferred embodiment, for the purpose of more clearly illustrating its construction, but without intent to indicate any specific dimensions and proportions.

In the drawings,-

. Fig. 1 is a perspective View of such switch in an operative position;

Fig. 2 is an end view of the switch;

Fig. 3 is a side view with a portion of the casing structure broken away and shown in section;

Fig. 4 is a plan view;

Fig. 5 is a detail section taken on line 5--5 of Fig. 4; and

Fig. 6 is a detail section taken on the line 6-45 of Fi 4.

Like reference characters designate the same parts wherever they occur in all the figures.

The contact members of the switch, that is, the parts involving the urely electrical equipment thereof, are em raced and enclosed in a casing or housing 1, which is provided with lugs 2 and 3 at its opposite ends. The lug 2 is adapted to serve as a clamp, and the lug 3 as a support and abutment for a clamping screw 4, complemental to the clamp 2 and adapted to cooperate with the latter in securing the switch to an instrument board or other support. The head of this screw is preferably formed with wings 5 so that it may be turned and set up by hand, making it unnecessary to use a wrench for attaching the switch to its support, although, of course, a wrench can be used if desired.

The electrical contact members 6 and 7 are preferably made from strips of resilient conductive metal bent at one end to form base or foot portions. Such footportions are separately held by the heads of binding screws 8 and 9 against a block 10 of insulating material, which in turn is held against the inside face of one end wall of the casing. The shanks of these screws pass through the foot portions of the contact strips, the insulating base, the adjacent end wall of the casing, and insulating washers 11 and 12, and carry on their protruding ends nuts 13 and 14, by which they are made fast, and binding nuts 15 and 16, by which the electrical conductors are gripped.

A plunger 17 passes through an opening in the opposite end wall of the casing and carries on its inner end a head or bridge contact 18 of electrically conductive material between the contact pieces 6 and 7. The latter are generally parallel to one another, but of undulatory form, spreading apart at their free ends, thenextending nearer to one another adjacent to said free ends, and again diverging.

The outer end of plunger 17 carries a head or knob 19, by which the plunger may be moved in and out. When moved in as far as it will go, as shown by full lines in Fig. 4, the head or bridge 18 is out of contact with the members 6 and 7, while a shoulder or washer 20 on the plunger next to such head, made of insulating material, prevents their coming into contact; but when pulled out to the dotted line position shown in Fig. 4, the head 18 bridges the gap between the contact members and completes the circuit through them. The inwardly offset and inclined portions of these spring contact members act as yielding detents to prevent accidental displacement, by jolting, of the switch plunger from one position to the other, but permit intentional displacement by exertion of moderate force.

The casing 1, with its lugs 2 and 3, is preferably made of pressed steel fashioned from a single blank of sheet steel. The lugs-2 and 3 then form integral extensions of the end walls projecting to the same side of the casing and approximately parallel to one another. The end walls are integral- 1y connected with intermediate side walls which underlie and embrace all but one side Fill of the space in which the electrical equipment is contained. These side walls are preferably substantially semi-cylindrical with tangent extensions, and are joined with the end walls on smooth longitudinal curves of short radius. The original blank is thus shaped by drawing operations with the use of suitably formed dies. After drawing, the junctions between the edges 21, 21 of the side walls and the edges of the end lugs 2 and 3 are trimmed to make clean and square corners by cutting away the metal which, after drawing, had partially filled up these corners. In thus trimming the casing, enough stock is left 011 the lugs 2 and 3 to form flanges 23 on the opposite side edges of the lug 2, and flanges 21 on the opposite edges of the lug 3.

After thus trimming the lugs, the flange 23 is again pressed between dies which form a lip 25 on its outer edge projecting toward the opposite lug and terminating in substantially the same plane with the flanges or lips 23. Said lips 23 and 25 are an important structural feature of the device, because they provide bearing edges in one plane, making extended peripheral contact with the surface of the support to which the switch is applied, and holding to such support with a firm grip. WVithout such lips the bearing of the lug on the support would be limited practically to an area in the middle part of the lug directly opposite to the end of the screw 4 and not much larger than the area of such end, offering very little resistance to pivotal movement of the casing about the axis of the screw or to loosening. But the flanges bring the bearing points of the lug out to its ed es whereby the resistance offered to each pivotal movement and loosening is greatly increased, and cause such bearing points to extend in a long but narrow line running the width of the lug 2 at its end and for a substantial distance along both sides back from such end. Thus when the switch is applied with the lug 2 on the front side of the instrument board, and the screw is set up, the turned in edges of the lug come to bear in a substantially even manner on the surface of the board, making a close and firm engagement therewith. Even if imperfect bearing should occur as to some parts of these flanges, there will inevitably be an extended enough bearing to hold the switch firmly in place.

In order to provide a sufficient length of bearing and threaded engagement between the lug 3 and the screw, the hole provided in the lug to receive the screw is punched in such a way that a lip 26 of substantial length is drawn from the rim of the hole toward the lug 2, forming a tube which is of su bstantially greater length than the thickness of the lug 3, and enabling a screw thread of several complete turns to be cut; thus affording a firm and strong nut or reaction abutment for the screw. The threaded passageway thus provided for the screw is not perpendicular to the lugs, but is so inclined that the angle between the axis of the screw and the outer projecting part of the lug 2 is less than a right angle. By virtue of this inclination, the pressure applied by the screw against the back of the instrument board tends to draw the switch as a whole upward or inward toward the edge of the board which is embraced by this lug and the screw, thereby making a close joint between the edges 21 of the casing and the adjacent edge of the board.

The end wall of the casing through which the switch plunger 17 passes is formed with an inwardly drawn lip 27, similar to the lip 26, to give a sufficient extended bearing for the plunger. A shoulder 17 is provided on the plunger outside of the casing to limit its penetration to substantially the amount shown in the drawings.

The open side of the casing, bounded between the edges 21 and the lugs 2 and 3, is closed by a detachable cover 28 of fiber or other insulating material, the width of which is approximately equal to the distance between the inner surfaces of the lugs, and its length equal to or slightly greater than the distance between the edges 21. The 0pposite ends of the cover rest on the edges 21 and its intermediate sides are preferably cut to an outline conforming to the lugs and their flanges. End flanges 29 to embrace the sides of the casing may beprovided on the ends of the cover, although they are not essential.

The holes in the casing wall through which the binding screws 11 and 12 pass are substantially larger than the screws, and the washers 11 and 12 which insulate the screws from the casing are not only perforated to fit the screws, but are off-set as well in the central portion to form a bushin shown at 11 in Fig. 6, which substantially fills the hole in the casing wall through which the screws pass. The peripheral part of the washer overlies the outer side of the casing and is clamped by the nut 13, thus holding its bushing portion in the wall, and making it impossible for the screw to come into conducting contact with the casing by any manner of careless mounting.

In speaking of the instrument board of an automobile as the mounting to which my switch may be applied, I have indicated merely one use out of many possible uses, and have typified all possible mounts by naming a specific one. Whether used in this specific relation, or otherwise, my invention has afforded a means by which an electric switch for any purpose, whether in a light ing circuit or in the electrical ignition cirly when considering the exposed face of theboard as its front face), and the switch may be applied to such flange, being then below the bottom of the board in back of its front face, whereby it is entirely concealed from the view of a person occupying the drivers seat. When applied in this manner and interEosed in the ignition system of the automo ile, it may serve as a very simple, yet effective means of delaying the attempt of an intending thief to start the engine of the car, and thereby preventing theft of the car.

What I claim and desire to secure by Letters Patent is:

1. An electric switch comprising a casing having side walls embracing an interior space, and end walls with extension lugs projecting from said end walls at one side, a screw threaded through one of said extension lugs and pro'ecting toward the other lug atsuch an inclination that the angle be? tween the axis of said screw and the projecting extremity of the opposite lug is less than a right angle, and switch contact members mounted within the embracing walls of said casing.

2. A casing for an electric switch comprising embracing end and side walls with extension lugs projecting to the same side from said end wal s, the intermediate part of the side walls which flank such open side,-

the cover bein adapted to cross such open side and over 1e the edges of the flanking side walls, and a clamping member mounted on one of said lugs opposite to the other lug and arranged to cooperate with the last named lug in clamping the casing on a suport. P 3. In an electric switch, an enclosing casing, a contact member within said casing, a binding screw supporting said contact member and passing throu h a wall of the casing, an insulating was er surroundin said screw and set against the face of sai wall, havin an offset central portion occupying the ho e in the wall through which the binding screw passes and likewise surrounding the screw, and an abutment on said screw bearing on the washer.

4. An electric switch comprisin a casin made of a single piece" of pressed s eet meta havin a curved central portion with tangent side wall extensions, end walls, and lugs projecting from said end walls at the same side of the casing as, and beyond, said side wall extensions, the before described parts 'being all integrally joined together and each lug having integral flanges extendin toward the other lug and joined in integra union with the end portions of the side wall extensions, and one of the lugs having also an end flange integrally joined with its side flanges and projecting toward the other lug, said other lu havin a hole and an integral lip surrounding sai hole and formingan extension thereof, said hole and lip being screw threaded, a clamping screw passing through said hole and meshing with the threads thereof, electrical contact members mounted within the casing on one of said end walls, and a complemental contact plunger passing through the opposite end wall of the casing and being movable therein, adapted to bridge across said contact members.

In testimony whereof I have afiixed my signature. I

JOSEPH POLLAK. 

